LAPACK 3.12.0 LAPACK: Linear Algebra PACKage
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## ◆ zaxpy()

 subroutine zaxpy ( integer n, complex*16 za, complex*16, dimension(*) zx, integer incx, complex*16, dimension(*) zy, integer incy )

ZAXPY

Purpose:
`    ZAXPY constant times a vector plus a vector.`
Parameters
 [in] N ``` N is INTEGER number of elements in input vector(s)``` [in] ZA ``` ZA is COMPLEX*16 On entry, ZA specifies the scalar alpha.``` [in] ZX ` ZX is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCX ) )` [in] INCX ``` INCX is INTEGER storage spacing between elements of ZX``` [in,out] ZY ` ZY is COMPLEX*16 array, dimension ( 1 + ( N - 1 )*abs( INCY ) )` [in] INCY ``` INCY is INTEGER storage spacing between elements of ZY```
Further Details:
```     jack dongarra, 3/11/78.
modified 12/3/93, array(1) declarations changed to array(*)```

Definition at line 87 of file zaxpy.f.

88*
89* -- Reference BLAS level1 routine --
90* -- Reference BLAS is a software package provided by Univ. of Tennessee, --
91* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
92*
93* .. Scalar Arguments ..
94 COMPLEX*16 ZA
95 INTEGER INCX,INCY,N
96* ..
97* .. Array Arguments ..
98 COMPLEX*16 ZX(*),ZY(*)
99* ..
100*
101* =====================================================================
102*
103* .. Local Scalars ..
104 INTEGER I,IX,IY
105* ..
106* .. External Functions ..
107 DOUBLE PRECISION DCABS1
108 EXTERNAL dcabs1
109* ..
110 IF (n.LE.0) RETURN
111 IF (dcabs1(za).EQ.0.0d0) RETURN
112 IF (incx.EQ.1 .AND. incy.EQ.1) THEN
113*
114* code for both increments equal to 1
115*
116 DO i = 1,n
117 zy(i) = zy(i) + za*zx(i)
118 END DO
119 ELSE
120*
121* code for unequal increments or equal increments
122* not equal to 1
123*
124 ix = 1
125 iy = 1
126 IF (incx.LT.0) ix = (-n+1)*incx + 1
127 IF (incy.LT.0) iy = (-n+1)*incy + 1
128 DO i = 1,n
129 zy(iy) = zy(iy) + za*zx(ix)
130 ix = ix + incx
131 iy = iy + incy
132 END DO
133 END IF
134*
135 RETURN
136*
137* End of ZAXPY
138*
double precision function dcabs1(z)
DCABS1
Definition dcabs1.f:47